WASHINGTON, Jan. 6, 2011 - Service members who suffer mild traumatic braininjuries in combat and then struggle with depression, irritability, alcoholabuse and similar problems after they return home most likely areexperiencing post-traumatic stress, rather than brain injury symptoms,according to a new study.

The study, sponsored by the Defense and Veterans Affairs departments andpublished in this month's Archives of General Psychiatry, a Journal of theAmerican Medical Association publication, tracked Minnesota National Guardsoldiers during the last month of their 16-month deployment to Iraq, thenagain a year after they returned home.

The findings, based on the self-reporting of 953 soldiers with follow-upsfrom the clinicians, showed "very little evidence for a long-term negativeimpact" from concussions or mild TBI on "psycho-social outcomes" –- anxiety,depression, drug and alcohol abuse and the like -- after accounting forpost-traumatic stress, said Melissa A. Polusny, a clinical psychologist atthe Minneapolis Veterans Affairs Health Care System and a professor atUniversity of Minnesota Medical School.

Polusny wrote the study along with five other clinical psychologists, and incollaboration with Army Col. (Dr.) Michael Rath, a surgeon with the 34thInfantry Division brigade that participated in the study.

"After we statistically controlled for PTSD symptoms, there were virtually nolong-term symptoms from concussive and mild TBI," she said.

Polusny emphasized that the study only investigated mild TBI, which may causea person to be momentarily dazed or confused or lose consciousness for fewerthan 20 minutes, but causes no actual injury to the brain or skull. Also, thestudy did not consider repeated head trauma -– the subject of other studiesthat have suggested long-term effects -– in the soldiers, 95 percent of whomwere on their first deployment to Iraq in 2005, she said.

The study's focus on mild TBI is significant for today's warfighters, Polusnysaid, because "the vast majority of reports of TBI are mild."

The study's findings, she added, are "very interesting and not exactly whatwe expected."

The findings show that service members are much more likely to reportconcussions and mild traumatic brain injuries after they return home thanthey are in the combat theater. Of those surveyed, only 9 percent reportedconcussions or TBI in theater, but 22 percent reported incidents afterredeployment.

Many of the soldiers who answered that they did not have mild TBI orpost-traumatic stress disorder symptoms actually did, the VA's publicationbrief of the study says. Of those, 64 percent reported having problems withdistractibility and irritability, 60 percent reported memory problems, 57percent reported ringing in the ears, and 23 percent had balance problems.

Another notable finding, Polusny said, is that after their return home, morethan 40 percent of the Iraq war veterans reported some levels of alcoholabuse.

"There's been a lot of attention paid to PTSD and mild TBI and even suiciderisk, but the prevalence of problem drinking appears to be much higher amongreturning service members than any of these other problems," she said.

Researchers were surprised at the wide difference in reporting from the wartheater to home, Polusny said. They believe the disparity may be due toservice members' reluctance to report problems while deployed, or that theyhave a different impression of events when they return home, she said. Thedifferences may reflect a need for better post-deployment questioning ofveterans, she added.

"One of the really important implications of the findings is that we need tobe carefully screening for PTSD, and make sure veterans receive treatment,"Polusny said.

Polusny added that the findings caused concern that combat veterans maymisattribute the reason for their problems, which could hamper treatment orcause a service member to not seek treatment.

"If a veteran is having irritability and memory problems, and assumes he hada concussion when maybe he is suffering from PTSD symptoms, ... we need tomake sure we are treating veterans for the right problems," she said.

The study did not investigate the cause of the PTSD or whether the TBItriggered it.

"The events that surround a concussion or mild TBI in theater -- beingexposed to a blast or being in a firefight -- those kinds of events alreadyplace someone at risk of PTSD," Polusny said. "Is that due to injury to thebrain, or the situation they are in? We can't piece that apart yet."